Computing devices, such as notebook computers, personal data assistants (PDAs), and mobile handsets, have user interface devices, which are also known as human interface device (HID). One user interface device that has become more common is a touch-sensor pad. A basic notebook touch-sensor pad emulates the function of a personal computer (PC) mouse. A touch-sensor pad is typically embedded into a PC notebook for built-in portability. A touch-sensor pad replicates mouse x/y movement by using two defined axes which contain a collection of sensor elements that detect the position of a conductive object, such as finger. Mouse right/left button clicks can be replicated by two mechanical buttons, located in the vicinity of the touchpad, or by tapping commands on the touch-sensor pad itself. The touch-sensor pad provides a user interface device for performing such functions as positioning a cursor, or selecting an item on a display. These touch-sensor pads can include multi-dimensional sensor arrays. The sensor array may be one dimensional, detecting movement in one axis. The sensor array may also be two dimensional, detecting movements in two axes.
FIG. 1A illustrates a conventional touch-sensor pad. The touch-sensor pad 100 includes a sensing surface 101 on which a conductive object may be used to position a cursor in the x- and y-axes. Touch-sensor pad 100 may also include two buttons, left and right buttons 102 and 103, respectively. These buttons are typically mechanical buttons, and operate much like a left and right button on a mouse. In some systems, these buttons may be touch-sensor buttons. These buttons permit a user to select items on a display or send other commands to the computing device.
FIG. 1B illustrates a conventional touch-sensor pad with a sub-region. The touch-sensor pad 150 includes a sub-region 152 defining an x-y region on which a conductive object may trigger a pre-defined function. When a conductive object contacts touch-sensor pad 150 at position x′-y′, the touch-sensor pad 150 reports the position and a host processor (not-shown) compares x′-y′ with the positions defined by the sub-region. If the conductive object is within the sub-region, the mapped function is triggered. Although not shown, touch-sensor pads, such as touch-sensor pad 150, often include several regions which may be utilized to trigger many functions.
One problem encountered with touch-sensor pad 150 is the consumption of processing resources associated with judging a conductive object's position in relation to one or more sub-regions of the touch sensor pad. When a touch-sensor pad includes one or more regions mapped to function, a host processor must determine an x-y position in which a presence of the conductive object was detected, whether the position is within a predefined sub-region, and what function is mapped to the region. Therefore, as more sub-regions are added to a touch-sensor pad, more processing resources are consumed.